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Six test-tubes contain aqueous solutions of FeSO4, H2SO4, Mn(NO3)2,H2O2, Pb(NO3)2, NaOH. 

(a) Identify the content of each test-tube without using other reagents. Write the results in tabular form. Write the equations for the chemical reactions used for the identification. 

(b) After identification, perform four reactions each time using three of the identified compounds and write the equations.  

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Reactions Observation  
(1) + (4)  FeSO4 + H2O2 → 2 Fe(OH)SO4 Colour change - yellowish (Fe3+
(1) + (5)  FeSO4 + Pb(NO3)2 → PbSO4 ↓ + Fe(NO3)2  Appearance of a white precipitate.
(1) + (6)  FeSO4 + 2NaOH → Fe(OH)2 ↓ + Na2SOFe(OH)2 + 1/2 O2 + H2O → Fe(OH)3 Appearance of a greenish white precipitate Fe(OH)2 which after oxidation by air turns into a reddish brown precipitate Fe(OH)3
(2) + (5)  H2SO4 + Pb(NO3)2 → PbSO4 ↓ + 2HNO3 Appearance of a white precipitate PbSO4
(3) + (6)  Mn(NO3)2 + 2NaOH → Mn(OH)2 + 2NaNO3
2 Mn(OH)2 + 1/2 O2 → MnMnO3 + 2H2
Mn(OH)2 + 1/2 O2 → MnO2 + H2
Appearance of a white precipitate Mn(OH)2 which after oxidation by air coverts into a brown-black precipitate MnMnO3 which eventually changes into MnO2 – a blackbrown precipitate. 
(5) + (6)  Pb(NO3)2 + 2NaOH → Pb(OH)2 + 2NaNO3 
Pb(OH)2 + 2NaOH → Na2Pb(OH)4
Appearance of a white precipitate Pb(OH)2 which dissolves in excess reagent. 
b) (1) + (2) + (4) 2 FeSO4 + H2O2 + H2SO4 → Fe2(SO4)3 + 2H2O Colour change → yellowish (Fe3+
(1) + (4) + (6)  2 FeSO4 + H2O2 + 4 NaOH → Fe(OH)3+ + 2Na2SO4 Appearance of a brown-reddish precipitate Fe(OH)3
(3) + (4) + (6) Mn(NO3)2 + H2O2 + 2 NaOH → MnO2 + 2 NaNO3+ 2H2O Appearance of a brown precipitate MnO2
(5) + (4) + (6) Pb(NO3)2 + H2O2 + 2 NaOH → PbO2 + 2 NaNO3 + 2H2O Appearance of a brown precipitate PbO2

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